In making Bessemer iron a higher temperature is allowable and the diameter may he 6,5 feet, at the tuyeres, and the blast inay.be irom 400° 0. to 500° C. (750° F. to 930° 1\), but even under this, practice, and still more surely in the making of pig for the Lancashire process, the temperature of the zone of fusion in the blast furnace is so low that sulphur cannot he eliminated in the slag, arid it is, therefore, necessary to roast the ores, even though they con* tain but a small quantity of pyrite. This roasting changes the condition of the iron from Fe:j04 to .Fe,03; and thereby reduces the: consumption of fuel in the blast furnace. In making Bessemer iron the aim is to get 1.00 per cent, silicon and from 1.50 to 3.00. per cent, manganese. The charcoal contains 85 per cent, of carbon, 3 per cent, of ash, and 12 per cent of moisture, and 600 to 1000 kg. of carbon are burned per 1000 kg. of pig-iron.
In 1897 there were 144 active furnaces; and allowing for the actual time in blast there was an average production of 13.1 tons per day. There were 130 works making wrought-iron and steel, and they averaged 12 tons per working day, which may give some idea of the scale of operations in Sweden. The average is no measure of the best, but in 1897 the largest blast furnaces were reckoned at 40 tons per day. In 1901 there were 139 blast furnaces giving an average daily product of 13.96 tons for the time they were in oper-, ation. In 1893 the production of Bessemer steel was, 84,400 tons, being a trifle more than the open-hearth, which was 81,890 tons. The Bessemer output increased to 114,120 tons in 1896, but it is' decreasing and in 1901 was only 77,231 tons, while the open-hearth product meanwhile steadily increased, until in 1900 it was 207,450 tons, there being a falling off in 1901 to 190,877 tons. During the year 1900 one-third of the Bessemer and one-fifth of the open-hearth, steel was made by the basic process, the basic Bessemer being used in only one works. The production of crucible steel amounts to a little over 1000 tons per year.
Sweden exports large quantities of iron and steel, the proportion varying according to business conditions, but there has been a tendency for the proportion to be less as the growth of basic processes has enabled other nations to make the purer grades of metal. In: 1840 she exported 86 per cent, of her wrought-iron and steel; in 1870, 62 per cent., and in 1897, 45 per cent. In 1890 the exports amounted to 225,000 tons and, in 1897. to 210,00,0 tons. In 1900